Identify AIS base stations and high-speed craft

Stations and aircraft are identified from speed, distance and time only. Other criteria (e.g. MMSIs with fewer than 9 digits) are not considered.

Usage

AISidentify_stations_aircraft(ais_data, crs_meters = 3035)

Arguments

ais_data

AIS data frame containing timestamp, lon, lat, and mmsi. timestamp must be Unix time (seconds since 1970-01-01), while lon and lat must be numeric. Another vessel identifier may be used if the column is named mmsi.

crs_meters

CRS (metres) used to calculate distances in the study area (defaults to EPSG:3035, Europe). Tip: use suggest_crs function (crsuggest package) to find a suitable CRS for your study area.

Value

The input AIS data with the following additional columns:

• station: Whether the MMSI is classified as a base station.

• high_speed: Whether the MMSI is classified as a high-speed craft.

• n_point_mmsi_initial_data: Number of valid AIS positions for the MMSI.

• id_mmsi_point_initial: Sequential identifier of each AIS position.

Examples

data("ais")

# Define the Unix time (seconds since 1970-01-01)
ais$timestamp <- as.numeric(lubridate::ymd_hms(ais$datetime))

# calculate the travelled distance, time, and speed:
ais <- AIStravel(ais_data = ais, crs_meters = 3035)

# Identify stations and aircrafts:
out <- AISidentify_stations_aircraft(ais_data = ais, crs_meters = 3035)